SSID and Wireless Networking

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Getty Images/JGI/Jamie Grill

An SSID (Service Set Identifier) is the primary name associated with an 802.11 wireless local area network (WLAN) including home networks and public hotspots. Client devices use this name to identify and join wireless networks.

On home Wi-Fi networks, a broadband router or broadband modem stores the SSID and allows administrators to change it. Routers can broadcast this name to help wireless clients find the network.

Creating an SSID

SSIDs are case-sensitive text strings. The SSID is a sequence of alphanumeric characters (letters or numbers) with a maximum length of 32 characters.

Makers of Wi-Fi home network router set a default SSID on the unit. Common default router names include:

  • Linksys
  • xfinitywifi
  • dlink
  • default

Wi-Fi routers let network administrators change the router name.

Using SSIDs

Wireless devices like phones and laptops scan the local area for networks broadcasting their SSIDs and present a list of names to users. A user can initiate a new network connection by picking a name from the list.

In addition to obtaining the network's name, a Wi-Fi scan also determines whether each network has wireless security options enabled. Wi-Fi devices screens often show secured networks with a lock symbol next to the SSID.

Most wireless devices keep track of the different networks a user joins and their connection preferences in user profiles.

In particular, users can set up a device to automatically join networks having certain SSIDs by saving that setting into their profiles.

Wireless routers offer the option to disable SSID broadcasting as a means to ostensibly improve Wi-Fi network security (the effectiveness of this technique is limited) Connecting to networks with SSID broadcast disabled requires the user to have manually created a profile with the name and other connection parameters.

Issues with SSIDs

Consider these ramifications of how wireless network names work:

  1. If a network does not have wireless security options enabled, anyone can connect to it by knowing only the SSID.
  2. Using a default SSID increases the likelihood that another nearby network will have the same name, confusing wireless clients.When a Wi-Fi device discovers two networks with the same name, it will prefer and may try auto-connecting to whichever one with a stronger radio signal, which may be the incorrect choice. In the worst case, a person may get dropped from their own home network and get re-connected to a neighbor's who does not have login protection enabled.
  3. The SSID chosen for a home network should contain only generic information. Some names (like "HackMeIfYouCan") unnecessarily entice thieves to target certain homes and networks over others.
  4. An SSID can contain publicly-visible offensive language or coded messages.